The invention described in this application relates to a camless engine wherein the valves associated with each of the cylinders in an internal combustion engine are controlled electronically. Feedback is provided to control modules for each of the cylinders to provide an indication of which of two revolutions in a two-revolution cycle of the crankshaft the engine is currently in.
Internal combustion engines have historically had a number of cylinders each provided with valves for controlling the flow of air and fuel to the individual cylinders in a predetermined spaced relationship relative to the other cylinders. Further, the ignition in each of the cylinders is controlled to be in the proper sequence relative to the injection of the air and fuel.
As the ignition occurs in each cylinder a crankshaft is driven. Typically a camshaft has been provided in addition to the crankshaft, and rotates to drive the valves in the proper sequence. There are a number of cylinders, with the cylinders firing in predetermined sequence across two revolutions of the crankcase. Thus, each cylinder must have its fuel and air injected and ignition caused once per each two revolutions of the driven crankshaft. Again, a separate camshaft typically provides this timing.
More recently, camless engines have been proposed to provide simple manufacture and assembly. With camless operation a signal is provided to a control module associated with each of the cylinders to cause the valves, spark plugs, etc. to operate in the proper sequence.
However, some method of providing feedback to the control modules of which of two revolutions in a two revolution cycle of the crankcase are currently occurring is necessary.
It is known to provide a wheel on the crankshaft wherein the wheel has a plurality of timing members. The timing members typically provide some indication of when a revolution of the crankshaft has been completed. Typically, a tone wheel may be provided with a space at a particular rotation position, and the space in signals is taken by the control as an indication that a particular point has been reached. Typically, the tone wheel is provided with a plurality of members each based by approximately 6xc2x0. However, two of the members are missing such that an indication is provided when a particular point in the revolution, in typically top dead center, is reached. However, such systems have not been utilized in conjunction with camless engines to provide an indication of which of the two rotations in a two-rotation cycle of the crankshaft are currently occurring. This has been unnecessary, since the camshaft has provided the indication.
In the disclosed embodiment of this invention, a signal from a crankshaft is common for each of the two revolutions in a two-revolution cycle for the associated cylinders. The output signal from the crankshaft is processed to provide an indication of which of the two revolutions is occurring at a particular point in time. In one embodiment, the signal from the crankshaft has a location identifying components such as the two missing signals mentioned above. When this rotation identifying signal is sensed, it causes a modification in the signal that varies between the two revolutions. Thus, in one preferred embodiment the signal passes through a flip-flop that switches between a one and zero, or off and on. The output of the flip-flop adds or subtracts a signal tone to the signal from the crankcase. More preferably, the addition or subtraction occurs at the point of the break in the signal mentioned above. Thus, on one of the two revolutions there will be the prior art two spaces, whereas in the other of the two revolutions a signal element will be added (or subtracted) such that only a single space (or three) is missing. In this fashion, a control module receiving the signal will be able to identify which of the two revolutions is currently ongoing.
In other embodiments, the signal is inverted between the two revolutions, such that the control modules can identify which of the two revolutions is currently occurring. In a further embodiment a component such as a flip-flop alternatively changes the pulse width between the two revolutions, again so the individual control modules can identify which particular revolution is ongoing at any one point in time.
As could be appreciated, the control modules associated with each of the individual cylinders are programmed to know when to operate to allow flow of air, and fuel, as well as to cause firing of their individual cylinders. This occurs at a predetermined point in each of the cycles of revolution. Further, each of the cylinders preferably only operates once per two revolution cycle. The signal provided to the control modules allows each control module to identify which of the two revolutions in any one cycle is ongoing, such that the control modules can operate in a proper sequence.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.